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General Kenneth Nichols and the Manhattan Project
Nichols
The Oak Ridger has published the latest in a series of articles about General Kenneth D. Nichols, the Manhattan Project, and the 1954 Atomic Energy Act. The series has been produced by Nichols’ grandniece Barbara Rogers Scollin and Oak Ridge (Tenn.) city historian David Ray Smith. Gen. Nichols (1907–2000) was the district engineer for the Manhattan Engineer District during the Manhattan Project.
As Smith and Scollin explain, Nichols “had supervision of the research and development connected with, and the design, construction, and operation of, all plants required to produce plutonium-239 and uranium-235, including the construction of the towns of Oak Ridge, Tennessee, and Richland, Washington. The responsibility of his position was massive as he oversaw a workforce of both military and civilian personnel of approximately 125,000; his Oak Ridge office became the center of the wartime atomic energy’s activities.”
Emiliano Masiello, Richard Sanchez, Igor Zmijarevic
Nuclear Science and Engineering | Volume 161 | Number 3 | March 2009 | Pages 257-278
Technical Paper | doi.org/10.13182/NSE161-257
Articles are hosted by Taylor and Francis Online.
The method of short characteristics is extended to two-dimensional heterogeneous Cartesian cells. The new application is intended for realistic pin-by-pin lattice calculations with an exact representation of the geometric shape of the pins, without need for homogenization. The method keeps the advantages of conventional discrete ordinates methods, such as fast execution, together with the possibility to deal with a large number of spatial meshes. Expansion bases, spatial integration, and balance conservation are discussed. A Fourier analysis of the method shows that the scheme preserves the asymptotic behavior of analytical transport. Two coarse-mesh finite difference acceleration techniques have also been analyzed and generalized with the use of Eddington's factors to speed up the rate of convergence of the inner iterations. Numerical examples for realistic configurations show the precision of the method and the efficiency of the accelerated iterations. An analytical stability analysis is also presented for studying the nonconverged behavior of the accelerated scheme, and we give numerical proof of chaotic behavior and the existence of bifurcations.